The present invention pertains to a method and apparatus for determining the solution viscosity of polymers. The solution viscosity of polymers is very important in the manufacturing of various polymers. It is used to determine if the molecular weight of the polymer is correct and that the distribution of various molecular weight components within the polymer are correct. The molecular weight of the polymer is important in the control of the production of the polymer.
In the past, various methods have been suggested for determining the solution viscosity of polymers. One approach has been the drying of a polymer sample, dissolving a known amount of the sample in a selected solvent and determining the viscosity of the solution. This requires precise temperature equilibrium of the solution and the elimination of any gas bubbles or incompletely / dissolved polymer in the solvent. Also, attempts have been made to estimate the viscosity from the pressure drop produced by the introduction of a sample of the polymer into a solvent stream. These attempts are only approximate unless it is possible to simultaneously measure the polymer concentration to ensure that the polymer concentration in the solution remains constant. In the absence of measurements of the polymer concentration in the solvent it is impossible to determine the solution viscosity.